Protective factors

Being physically active

Various studies have shown that physical activity can reduce the risk of breast cancer.

An analysis of 31 studies found that women who did the most activity had a 12% lower risk of developing breast cancer compared with the least active women.

The analysis also showed that the more active a woman is, the more she can reduce her risk of breast cancer. For example, for every 2 hours a week a woman spends doing moderate to vigorous activity, the risk of breast cancer falls by 5%.

Activity can include:

having a physically active job

recreational exercise, such as walking, cycling or playing sport

chores such as ironing, gardening and cleaning

The reduced risk is probably because exercise lowers levels of insulin, hormones and growth factors in the body.

Breastfeeding

Breastfeeding lowers the risk of developing breast cancer, particularly if you have your children when you are younger. The longer you breastfeed the more the risk is reduced.

It is not completely clear why this is. But the reduced risk might be because the ovaries don't produce eggs so often during breastfeeding. Or it might be because breastfeeding changes the cells in the breast so they might be more resistant to changes that lead to cancer.

Aspirin and anti inflammatory drugs

Research has shown that women who regularly take aspirin or other non steroidal anti inflammatory medicines have a slightly lower risk of developing breast cancer.

Remember though that aspirin can irritate the lining of your stomach and cause bleeding. So you should talk to your own GP before starting to take it regularly.

You shouldn't take these medicines if you have any history of stomach ulcers.

Medicines for women at higher risk

Some women who have family members with breast cancer have a higher risk of developing it than other women. Some medicines can help to prevent breast cancer in women at high risk. Taking a drug called anastrozole for 5 years can reduce the risk of breast cancer.

Recent research showed that if 1,000 women at high risk of breast cancer took anastrozole for 5 years, it prevented 35 cases of breast cancer. In women taking a similar drug called tamoxifen 21 breast cancers would be prevented.

Speak to your doctor if you have family members with breast cancer and you think you might be at risk of developing it.

The information on this page is based on literature searches and specialist checking. We used many references and there are too many to list here. If you need additional references for this information please contact patientinformation@cancer.org.uk with details of the particular risk or cause you are interested in.

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